Generic proactive SS call forwarding control

GSM A-I/F DTAP - Register
    Protocol Discriminator: Non call related SS messages (11)
        .... 1011 = Protocol discriminator: Non call related SS messages (0xb)
        0... .... = TI flag: allocated by sender
        .000 .... = TIO: 0
    01.. .... = Sequence number: 1
    ..11 1011 = DTAP Non call Supplementary Service Message Type: Register (0x3b)
    Facility
        Element ID: 0x1c
        Length: 16
        GSM Mobile Application
            Component: invoke (1)
                invoke
                    invokeID: 0
                    opCode: localValue (0)
                        localValue: interrogateSS (14)
                    ss-Code: cfu - call forwarding unconditional (33)
                    basicService: teleservice (3)
                        teleservice: allSpeechTransmissionServices (16)
    SS Version Indicator
        Element ID: 0x7f
        Length: 1
        SS Version Indicator: Phase 2 service, ellipsis notation, and phase 2 error handling is supported